Depth of gon, fan-shaped and tabs-shaped gate should be 0.7 to 0.9t(t is the wall thickness of product), the diameter of pin gate should be 0.8to 2mm The product with lower viscosity should choose the smaller size. For the wall thickness is more than 4mm, the diameter of the flow channel should be 8-12mm. The optimum angle is 5 to 7, if the products of injecting molding are 4mm or more, the angle should be 7, the diameter of the mainstream channel is 8 to 10 mm, the overall length of the gate should not exceed 50 mm.įor the products with wall thickness less than 4mm, the diameter of the flow channel should be 6-8mm. Mold temperature can be 60 -80 Celsius degree, The diameter of the sprue should match up with the internal taper. In addition, PMMA must use drying hopper to store material. If you need higher strength requirements of products, you should use a larger aspect ratio of the screw to implement low-temperature plastics. Due to the great melt viscosity, it requires the grooves deeper and nozzle hole a larger diameter. The PMMA material doesn’t have special requirements for the injection molding machine.
Usually, it can reach 30%, you should make sure there is no pollution of recycled materials, or it will influence the transparency and the nature of the finished products. The actual quantity depends on the requirements for quality. In some cases, the utilization of recycled materials can reach 100%. Dying temperature is 80-90 Celsius degree and drying time is 3 hours or above. The presence of moisture makes the melt bubbles, gas lines, and low transparency. The injection molding moisture must be less than 0.1%. PMMA has a certain degree of water absorption of 0.3-0.4%. PMMA is an amorphous polymer, the melt temperature is above 160 Celsius degree and the decomposition temperature can reach 270 Celsius degree. In molding, it changes the melt viscosity mainly from the injection temperature. The fluidity of PMMA is poorer than that of PS, ABS and its melt viscosity is rather sensitive to the change of temperature. If you add a small amount of nitrile rubber (about 50%) in the 372 PMMA, it will become 373 PMMA. 372 PMMA is the copolymer of methyl methacrylate and styrene. PMMA has some defects such as low surface hardness, easy to snag, low impact resistance, poor molding liquidity performance, so PMMA’s modification appears one after another such as copolymerization between methyl methacrylate and styrene and butadiene, a blend of PMMA and PC, etc. PMMA is commonly known as polymethyl methacrylate, acrylic and so on and its chemical name is polymethyl methacrylate. Injection Molding Technology of Polymethyl Methacrylate (PMMA)
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